///////////////////////////////////////////////////////////////////////////

//

// Copyright (c) 2004, Industrial Light & Magic, a division of Lucas

// Digital Ltd. LLC

// 

// All rights reserved.

// 

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

// *       Redistributions of source code must retain the above copyright

// notice, this list of conditions and the following disclaimer.

// *       Redistributions in binary form must reproduce the above

// copyright notice, this list of conditions and the following disclaimer

// in the documentation and/or other materials provided with the

// distribution.

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// its contributors may be used to endorse or promote products derived

// from this software without specific prior written permission. 

// 

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

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///////////////////////////////////////////////////////////////////////////

//-----------------------------------------------------------------------------

//

//	class EnvmapImage

//

//-----------------------------------------------------------------------------

#include "EnvmapImage.h"

#include <ImathFun.h>

#include "namespaceAlias.h"

using namespace IMF;

using namespace IMATH;

EnvmapImage::EnvmapImage ():

    _type (ENVMAP_LATLONG),

    _dataWindow (V2i (0, 0), V2i (0, 0)),

    _pixels (1, 1)

{

    clear();

}

EnvmapImage::EnvmapImage (Envmap type, const Box2i &dataWindow):

    _type (type),

    _dataWindow (dataWindow),

    _pixels (dataWindow.max.y - dataWindow.min.y + 1,

	     dataWindow.max.x - dataWindow.min.x + 1)

{

    clear();

}

void

EnvmapImage::resize (Envmap type, const Box2i &dataWindow)

{

    _pixels.resizeEraseUnsafe (dataWindow.max.y - dataWindow.min.y + 1,

			       dataWindow.max.x - dataWindow.min.x + 1);

    _type = type;

    _dataWindow = dataWindow;

    clear();

}

void

EnvmapImage::clear ()

{

    int w = _dataWindow.max.x - _dataWindow.min.x + 1;

    int h = _dataWindow.max.y - _dataWindow.min.y + 1;

    for (int y = 0; y < h; ++y)

    {

	for (int x = 0; x < w; ++x)

	{

	    Rgba &p = _pixels[y][x];

	    p.r = 0;

	    p.g = 0;

	    p.b = 0;

	    p.a = 0;

	}

    }

}

Envmap		

EnvmapImage::type () const

{

    return _type;

}

const Box2i &

EnvmapImage::dataWindow () const

{

    return _dataWindow;

}

Array2D<Rgba> &

EnvmapImage::pixels ()

{

    return _pixels;

}

const Array2D<Rgba> &

EnvmapImage::pixels () const

{

    return _pixels;

}

namespace {

V2f

dirToPosLatLong (const Box2i &dataWindow, const V3f &dir)

{

    return LatLongMap::pixelPosition (dataWindow, dir);

}

V2f

dirToPosCube (const Box2i &dataWindow, const V3f &dir)

{

    CubeMapFace face;

    V2f posInFace;

    CubeMap::faceAndPixelPosition (dir, dataWindow, face, posInFace);

    return CubeMap::pixelPosition (face, dataWindow, posInFace);

}

} // namespace

Rgba

EnvmapImage::filteredLookup (V3f d, float r, int n) const

{

    //

    // Filtered environment map lookup: Take n by n point samples

    // from the environment map, clustered around direction d, and

    // combine the samples with a tent filter.

    //

    //

    // Depending on the type of map, pick an appropriate function

    // to convert 3D directions to 2D pixel poitions.

    //

    V2f (* dirToPos) (const Box2i &, const V3f &);

    if (_type == ENVMAP_LATLONG)

	dirToPos = dirToPosLatLong;

    else

	dirToPos = dirToPosCube;

    //

    // Pick two vectors, dx and dy, of length r, that are orthogonal

    // to the lookup direction, d, and to each other.

    //

    d.normalize();

    V3f dx, dy;

    if (abs (d.x) > 0.707f)

	dx = (d % V3f (0, 1, 0)).normalized() * r;

    else

	dx = (d % V3f (1, 0, 0)).normalized() * r;

    dy = (d % dx).normalized() * r;

    //

    // Take n by n point samples from the map, and add them up.

    // The directions for the point samples are all within the pyramid

    // defined by the vectors d-dy-dx, d-dy+dx, d+dy-dx, d+dy+dx.

    //

    float wt = 0;

    float cr = 0;

    float cg = 0;

    float cb = 0;

    float ca = 0;

    for (int y = 0; y < n; ++y)

    {

	float ry = float (2 * y + 2) / float (n + 1) - 1;

	float wy = 1 - abs (ry);

	V3f ddy (ry * dy);

	for (int x = 0; x < n; ++x)

	{

	    float rx = float (2 * x + 2) / float (n + 1) - 1;

	    float wx = 1 - abs (rx);

	    V3f ddx (rx * dx);

	    Rgba s = sample (dirToPos (_dataWindow, d + ddx + ddy));

	    float w = wx * wy;

	    wt += w;

	    cr += s.r * w;

	    cg += s.g * w;

	    cb += s.b * w;

	    ca += s.a * w;

	}

    }

    wt = 1 / wt;

    Rgba c;

    c.r = cr * wt;

    c.g = cg * wt;

    c.b = cb * wt;

    c.a = ca * wt;

    return c;

}

Rgba

EnvmapImage::sample (const V2f &pos) const

{

    //

    // Point-sample the environment map image at 2D position pos.

    // Interpolate bilinearly between the four nearest pixels.

    //

    int x1 = IMATH::floor (pos.x);

    int x2 = x1 + 1;

    float sx = x2 - pos.x;

    float tx = 1 - sx;

    x1 = clamp (x1, _dataWindow.min.x, _dataWindow.max.x) - _dataWindow.min.x;

    x2 = clamp (x2, _dataWindow.min.x, _dataWindow.max.x) - _dataWindow.min.x;

    int y1 = IMATH::floor (pos.y);

    int y2 = y1 + 1;

    float sy = y2 - pos.y;

    float ty = 1 - sy;

    y1 = clamp (y1, _dataWindow.min.y, _dataWindow.max.y) - _dataWindow.min.y;

    y2 = clamp (y2, _dataWindow.min.y, _dataWindow.max.y) - _dataWindow.min.y;

    Rgba p11 = _pixels[y1][x1];

    Rgba p12 = _pixels[y1][x2];

    Rgba p21 = _pixels[y2][x1];

    Rgba p22 = _pixels[y2][x2];

    Rgba p;

    p.r = (p11.r * sx + p12.r * tx) * sy + (p21.r * sx + p22.r * tx) * ty;

    p.g = (p11.g * sx + p12.g * tx) * sy + (p21.g * sx + p22.g * tx) * ty;

    p.b = (p11.b * sx + p12.b * tx) * sy + (p21.b * sx + p22.b * tx) * ty;

    p.a = (p11.a * sx + p12.a * tx) * sy + (p21.a * sx + p22.a * tx) * ty;

    return p;

}